1. Field of the Invention
The present invention relates to a mobile communication method and a mobile communication system, which perform communications between an originating terminal and a terminating terminal through a radio access network and a core network, and to a session control device and an originating terminal, which are used in the mobile communication method.
2. Description of the Related Art
With reference to FIGS. 1 and 2, descriptions will be given of a conventional mobile communication method of performing communications between an originating terminal and a terminating terminal through a radio access network and a core network.
In Step S4001, an originating terminal 10A sends a communication start request (a call request) which requests to start communications with a terminating terminal 10B, to a session control device 30A controlling a location area of the originating terminal 10A.
In Step S4002, the session control device 30A performs an authentication process for the originating terminal 10A in response to the received communication start request, and then in Step S4003, the result of the authentication is sent to the originating terminal 10A.
In Step S4004, when the result of authentication is affirmative, the originating terminal 10A sends a bearer setup request (a U-plane bearer setup request) which requests to set a bearer for communications between the originating terminal 10A and the terminating terminal 10B, to the session control device 30A.
In Step S4005, the session control device 30A inquires of a terminal location management device 50 about a location area of the terminating terminal 10B (location information).
In Step S4006, the session control device 30A obtains the location area of the terminating terminal 10B from the terminal location management device 50.
In Step S4007, the session control device 30A sends a communication start request for the terminating terminal 10B to a session control device 30B controlling the obtained location area of the terminating terminal 10B.
In Step S4008, the session control device 30B sends a communication start request (a calling signal, paging) for the terminating terminal 10B.
In Step S4009, the terminating terminal 10B sends a response to the received communication start request to the session control device 30B.
In Step S4010, the session control device 30B transfers the received response to the session control device 30A, and in Step S4011, the session control device 30A transfers the received response to the originating terminal 10A.
In Step S4012, communication conditions including a communication quality, a communication speed and the like are negotiated between the originating terminal 10A, which has received the above-mentioned response, and the terminating terminal 10B, and between the session control device 30A and the session control device 30B.
In Step S4013a, the session control device 30A sends to a radio bearer setup device 60A a radio bearer setup command which commands to set a radio bearer in a radio access network, in response to the above-mentioned negotiation result.
In Step S4014a, the radio bearer setup device 60A sets a radio bearer between the radio bearer setup device 60A and the originating terminal 10A in the radio access network.
Moreover, in Step S4015a, the session control device 30A sends to a network bearer setup device 70A a network bearer setup command which commands to set a network bearer in a core network, in response to the above-mentioned negotiation result.
In Step S4016a, the network bearer setup device 70A sets the network bearer in the core network used for communications between the originating terminal 10A and the terminating terminal 10B.
Similarly, in Step S4013b, the session control device 30B sends to a radio bearer setup device 60B a radio bearer setup command which commands to set a radio bearer in the radio access network, in response to the above-mentioned negotiation result.
In Step S4014b, a radio bearer in the radio access network between the radio bearer setup device 60B and the terminating terminal 10B is set.
Furthermore, in Step S4015b, the session control device 30B sends to a network bearer setup device 70B a network bearer setup command which commands to set a network bearer in the core network, in response to the above-mentioned negotiation result.
In Step S4016b, the network bearer setup device 70B sets the network bearer in the core network used for communications between the originating terminal 10A and the terminating terminal 10B.
In Step S4017, the originating terminal 10A starts communications with the terminating terminal 10B by use of the set radio and network bearers.
In the conventional mobile communication method, when the originating terminal 10B is out of the coverage area or is during communication, it is configured that network resources (especially the radio bearer on the originating terminal 10A side) is not used wastefully.
However, in the conventional mobile communication method, as described above, it is required to sequentially perform steps necessary to start communications between the originating terminal 10A and the terminating terminal 10B.
Therefore, there has been a problem in that connection delay, which is the time from the sending of a call request to the time the communication is started, is long.